!   D01UAF Example Program Text
!   Mark 27.3 Release. NAG Copyright 2021.

    Module d01uafe_mod

!     D01UAF Example Program Module:
!            Parameters and User-defined Routines

!     .. Use Statements ..
      Use nag_library, Only: nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Accessibility Statements ..
      Private
      Public                           :: d01uaf_f
!     .. Parameters ..
      Integer, Parameter, Public       :: i_funid = 1
      Integer, Parameter, Public       :: liuser = i_funid
      Integer, Parameter, Public       :: lruser = 1
    Contains
      Subroutine d01uaf_f(x,nx,fv,iflag,iuser,ruser)

!       .. Implicit None Statement ..
        Implicit None
!       .. Scalar Arguments ..
        Integer, Intent (Inout)        :: iflag
        Integer, Intent (In)           :: nx
!       .. Array Arguments ..
        Real (Kind=nag_wp), Intent (Out) :: fv(nx)
        Real (Kind=nag_wp), Intent (Inout) :: ruser(*)
        Real (Kind=nag_wp), Intent (In) :: x(nx)
        Integer, Intent (Inout)        :: iuser(*)
!       .. Intrinsic Procedures ..
        Intrinsic                      :: exp, log
!       .. Executable Statements ..
        Select Case (iuser(i_funid))
        Case (1)
          fv = 4.0E0_nag_wp/(1.0E0_nag_wp+x*x)
        Case (2)
          fv = 1.0E0_nag_wp/(x*x*log(x))
        Case (3)
          fv = exp(-x)/x
        Case (4)
          fv = 1.0E0_nag_wp/x
        Case (5)
          fv = exp(-3.0E0_nag_wp*x*x-4.0E0_nag_wp*x-1.0E0_nag_wp)
        Case (6)
          fv = exp(2.0E0_nag_wp*x+2.0E0_nag_wp)
        Case Default
          iflag = -1
        End Select
      End Subroutine d01uaf_f
    End Module d01uafe_mod
    Program d01uafe

!     D01UAF Example Main Program

!     .. Use Statements ..
      Use d01uafe_mod, Only: d01uaf_f, i_funid, liuser, lruser
      Use nag_library, Only: d01uaf, nag_wp
!     .. Implicit None Statement ..
      Implicit None
!     .. Parameters ..
      Integer, Parameter               :: nout = 6
!     .. Local Scalars ..
      Real (Kind=nag_wp)               :: a, b, dinest
      Integer                          :: funid, i, ifail, key, nstor
!     .. Local Arrays ..
      Real (Kind=nag_wp)               :: ruser(lruser)
      Integer                          :: iuser(liuser)
!     .. Executable Statements ..
      Write (nout,*) 'D01UAF Example Program Results'

cases: Do funid = 1, 6
        Write (nout,*)
        Select Case (funid)
        Case (1)
          Write (nout,*) 'Gauss-Legendre example'
          a = 0.0_nag_wp
          b = 1.0_nag_wp
          key = 0
        Case (2)
          Write (nout,*) 'Rational Gauss example'
          a = 2.0_nag_wp
          b = 0.0_nag_wp
          key = -5
        Case (3)
          Write (nout,*) 'Gauss-Laguerre example (adjusted weights)'
          a = 2.0_nag_wp
          b = 1.0_nag_wp
          key = -3
        Case (4)
          Write (nout,*) 'Gauss-Laguerre example (normal weights)'
          a = 2.0_nag_wp
          b = 1.0_nag_wp
          key = 3
        Case (5)
          Write (nout,*) 'Gauss-Hermite example (adjusted weights)'
          a = -1.0_nag_wp
          b = 3.0_nag_wp
          key = -4
        Case (6)
          Write (nout,*) 'Gauss-Hermite example (normal weights)'
          a = -1.0_nag_wp
          b = 3.0_nag_wp
          key = 4
        End Select
        iuser(i_funid) = funid

        Do i = 1, 6
          nstor = 2**(i)
          ifail = -1
          Call d01uaf(key,a,b,nstor,d01uaf_f,dinest,iuser,ruser,ifail)
          Select Case (ifail)
          Case (:-1)
!           Error flag returned by d01uaf_f
            Exit cases
          Case (0,1)
!           The definite integral has been estimated.
            Write (nout,99999) nstor, dinest
          Case Default
!           Illegal parameters on entry to d01uaf
            Exit cases
          End Select
        End Do
        Write (nout,*)

      End Do cases

99999 Format (1X,I5,' Points     Answer = ',F10.5)
    End Program d01uafe